Today network operators are faced with an exponential increase in traffic demand. To cope with this network operators are increasingly trying to upgrade their network capacities to satisfy these demands.
When the user traffic demand exceeds the network capacity of a radio access network RAN it leads to congestion in the whole network. Congestion in radio access networks is nowadays one of the most important challenges currently being faced by network operators. Conventionally in 3GPP various mechanisms are devised to report congestion from the radio access network to the core network, e.g. disclosed in the non-patent literature 3GPP, “TR 23.705, System Enhancements for User Plane Congestion Management” so that the core network can take mitigating actions such as applications specific traffic limiting, consider subscriber profiles and operator policies for overcoming congestion into account.
FIG. 1 shows a conventional mobile network comprising a user equipment UE connected to a radio access network RAN which is further connected to a core network in the user plane and control plane. The core network is further connected to IP services and the Internet. Reference sign 1 in FIG. 1 indicates that the radio access network RAN should be able to detect congestion in an unambiguous manner. The radio access network RAN may then indicate the congestion 2 to the core network. The core network then may initiate core network-based congestion mitigation 4 and provide service and/or quality of service information for radio access network-based congestion mitigation to the radio access network RAN. The radio access network RAN then provides radio access network based congestion mitigation which is indicated with reference sign 5b. These actions 1-5b may be involved between the radio access network and the core network for congestion detection, reporting by using control plane/user plane interfaces or using off-path methods and mitigation actions are done at the core network to alleviate congestion.
In the non-patent literature of 3GPP, “TS 36.314, Evolved Universal Terrestrial Radio Access (E-UTRA); Layer 2—Measurements” various metrics have been defined to measure different parameters in base stations of the radio access network like an evolved nodeB or the like. Most of these parameters when used in isolation cannot give any indication of congestions, since they could exceed some pre-configured thresholds under non-congested situations as well. For example the physical resource block PRB utilization in the radio access network the following measurement is defined
                              M          ⁡                      (            T            )                          =                  ⌊                                                    M                ⁢                                                                  ⁢                1                ⁢                                  (                  T                  )                                                            P                ⁡                                  (                  T                  )                                                      *            100                    ⌋                                    (        1        )            
However this measurement in isolation does not indicate a congestion since 100% physical resource block utilization could also indicate several user equipment UE in bad radio conditions, or depending on modulation and coding scheme selection/scheduling strategies, the physical resource block PRB utilization can be maximized even when the radio access network is not congested. Similar problems exist with other currently defined measurements such as scheduled IP throughput, data loss, the number of active user equipment or the like.